At the present time there are on the market multifunctional analog hand watches, comprising several stepping motors independently driving several gear trains. In the most simple version, two motors drive two hands, but one could also have three, four or five motors each driving one or even several hands, likewise combinations with digital displays. This is the case, for example, with the clockwork-movements 251.262 and 251.272 which have already been marketed for several years by ETA in Grenchen (Switzerland), and also the clockwork-movement disclosed in patent EP A O 247.520, corresponding to U.S. Pat. No. 4,748,603.
These configurations allow a number of additional functions, over and above classical timekeeping functions, to be displayed simultaneously or successively, for example the hours, minutes and seconds of a chronograph function.
Another of the most prevalent additional functions is without doubt the date. This date function can be simple, semi-perpetual, or perpetual. In the latter case, in addition to the date, it is necessary to program the month and leap year. Moreover, the date can be complemented by the display of the phases of the moon.
One of the principal difficulties is to display clearly the number of days in the month which can vary from 28 to 31, which presupposes, particularly in the case of an analog hand display, a special scale often difficult to read, as can be seen in the above mentioned patent.